Rainbow Quartz has mauve-rose skin and voluminous platinum-blonde hair which appears to be a mix of Pearl and Rose's hair. It is long, large, and wavy (Rose), while each individual tuft ends in a distinctive point (Pearl). It is shaded with pale mint-green and pastel pinkish-peach. However, this may be due to the effects of the pink and yellow spotlights. She possesses only a single pair of arms, and is slender and curvaceous with a tall stature, standing a head or two taller than Opal. Rainbow Quartz possesses two pairs of eyes; the top pair of eyes (Pearl) are larger and more rounded and colored a pale-indigo, whereas the bottom pair (Rose) are thinner and more shapely with black pupils. Her nose is shapely and pointed like Pearl's nose, but short with discernible nostrils like Rose's. She also has defined lips that are similar to Rose's, although Rainbow Quartz's lips lack the sheen of Rose's.
Rainbow Quartz wears a sleeveless, skin-tight pinkish-peach bodice with violet high-leggings. There is a stylized, four-pointed star, with the left and right sides of the star bent upwards, cut-out on the stomach area of the bodice where Rose's gem is. She also wears a loose, sheer, transparent long-sleeved, bright and pastel blue blouse with lime-green outlines over her upper body. Her outfit includes no footwear, but instead has long, magenta leg-warmers that cover half of her lower legs and feet.
Rainbow Quartz is assumed to possess standard Gem abilities and traits. Being a fusion of Pearl and Rose Quartz, it can be assumed that she is a very strong warrior, like Rose, and is very quick, like Pearl.
She is very agile and graceful, as she is able to stand on the tips of her toes and execute acrobatics. Her weapon is yet to be seen, as she was only formed by Rose and Pearl for Greg Universe's video.
- Rainbow Quartz, along with Sapphire and Peridot has yet to summon her weapon.
- Her appearance bears a striking resemblance to the character Danse from the cartoon series Jem.
- Her outfit closely resembles an 80s-90s dancing/workout outfit.
- She was the first fusion on-screen to de-fuse of her own will. Other fusions have been damaged or broken, or have fallen out of sync. Sardonyx was the second. Sugilite is the third in her appearance in "Cry for Help", when Garnet fused with Amethyst in order to quickly destroy the Gem Communication Hub.
- Her formation was the first time Greg saw Gems fusing.
- Rainbow Quartz is the first fusion revealed to involve Rose Quartz.
- Her eyes seem to be expressing the different emotion of each of her parts towards Greg, a loving look from Rose's eyes and a cocky/boastful look from Pearl's.
- Her skin and gemstones color are unknown, since the pinkish coloration could have just been the tinted lighting.
- Assuming that Steven and Pearl are able to fuse, Rainbow Quartz's design would differ from her debut.